1. Field of the Invention
The invention relates to a microchip testing device in which blood analyses are carried out by the process of absorptiometry (a diagnostic technique using computerized analysis of absorption rates of photons directed in a focused beam at a test object) using a microchip after completion of a centrifugal process.
2. Description of Related Art
Recently an analysis method using a microchip called “μ-TAS” or “Lab.on a-chip’ has been considered in which using precision processing technology of semiconductors and micromachine production technology chemical analyses and the like are performed in a more precise manner as compared to a conventional device. In the case of using μ-TAS for medical fields there are the following and similar advantages:
(1) By reducing the amount of sample, such as, for example, blood, the burden on the patient can be reduced.
(2) The amount of reagent can be reduced and the study costs can be reduced.
(3) Since the device is small, the study can be easily carried out.
In an analysis by the absorptiometry process using a microchip, a series of operations which is described below is carried out and the concentration of a desired enzyme which is contained in the blood plasma is measured. These operations are:
(1) Blood which was taken using a painless needle is delivered into the chip.
(2) The blood in the microchip undergoes centrifugal treatment and is separated into plasma and blood cells.
(3) The plasma and reagent are uniformly mixed and a sample liquid is produced therefrom.
(4) The sample liquid is delivered into the part for measuring absorbance.
(5) The sample liquid which was delivered into the part for measuring absorbance is irradiated with light from a light source and the amount of attenuation of light with a certain wavelength is measured.
For example, Japanese Patent Application Publication JP-A-2006-110491 describes a centrifugal device for a microchip in which a microchip filled with blood as the sample is subjected to a centrifugal force, and thus centrifugal separation is performed in which the blood is separated into plasma and blood cells by the difference between specific weights, in which the plasma is mixed with a reagent and a sample liquid produced therefrom, and in which the sample liquid is fed into the part for measuring absorbance. Afterwards the microchip from which the sample liquid was obtained is taken from the centrifugal device for the microchip, the sample liquid which filled the part for measuring absorbance is irradiated with light from a light source and the amount of attenuation of light with a certain wavelength and the concentration of the desired enzyme which is contained in the plasma are measured.
FIG. 21 shows an example of a conventional centrifugal device which is used for blood analyses. This centrifugal device is made such that a chip holder 102 in which the microchip 101 is held, is placed on the centrifugal rotor 103 of the centrifugal device, that the rotation of the rotary drive source 104 is transferred via a main shaft 105 to the centrifugal rotor 103 and that a speed of at least 3000 rpm is produced by the rotary drive source 104.
In conducting an analysis by the absorptiometry process using this centrifugal device, first the microchip 101 in the chip holder 102 is placed on the centrifugal rotor 103, the centrifugal rotor 103 is turned and the blood is separated into plasma and blood cells. Next, the chip holder is turned automatically by the switching mechanism of the centrifugal direction 106. Afterwards the centrifugal rotor 103 is turned again to switch the direction of the centrifugal force which is being applied to the microchip 101. At this point, the plasma is mixed with the reagent, a sample liquid is thus produced and the sample liquid is fed into the part for measuring absorbance. Afterwards the microchip 101 is taken from the centrifugal device, it is held in the device for testing absorbance (not shown), the sample liquid which has filled the part for measuring absorbance is irradiated with light from a light source and the amount of attenuation of light with a certain wavelength and the concentration of the desired enzyme which is contained in the plasma are measured.
In the conventional centrifugal device as shown in FIG. 21, however, to conduct the analysis by the absorptiometry process, the microchip had to be removed from the centrifugal device, placed in the device for testing absorbance, the part for measuring absorbance of the microchip had to be irradiated with light from the light source, and the amount of attenuation of light with a certain wavelength had to be measured. The diameter of the cross section which is perpendicular to the optical axis of the part for measuring absorbance of the microchip is, for example, a 1.0 mm. Irradiation with light had to be exact to prevent scattered light travelling to outside the part for measuring absorbance of the microchip. If the microchip is not held exactly in the device for testing absorbance, the optical path of the light which is transmitted by the part for measuring absorbance is slightly lengthened so that the amount of light attenuation increases. It was possible for this to lead to incorrect test results. Since, in this way, for analyses by the absorptiometry process, a precise device for testing absorbance is required, it was difficult to carry out analyses by the absorptiometry process of the microchip on the centrifugal rotor of the centrifugal device.
In the above described conventional centrifugal device, it was necessary to carry out centrifugal separation by rotation of the centrifugal rotor, afterwards to actuate the switching mechanism of the centrifugal direction by a tester or the like, to subject the chip holder to autorotation, switch the centrifugal direction, turn the centrifugal rotor again, furthermore, to remove the microchip from the centrifugal device by the tester or the like, place it in the device for testing absorbance and test it. The tester or the like was never able to leave the centrifugal device and the device for testing absorbance. Therefore, special testers or the like had to be delegated for conducting blood analyses by the absorptiometry process, with the resulting disadvantage of additional personnel costs and the like.